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| author | Matt Fleming <matt@codeblueprint.co.uk> | 2016-03-01 00:22:52 +0300 |
|---|---|---|
| committer | Matt Fleming <matt@codeblueprint.co.uk> | 2016-09-09 18:08:34 +0300 |
| commit | 816e76129ed5fadd28e526c43397c79775194b5c (patch) | |
| tree | de3ec000aa5bb1fdbc6d652fbd4db9da0e82ebda /include/linux/efi.h | |
| parent | c45f4da33a297f85435f8dccb26a24852ea01bb9 (diff) | |
| download | linux-816e76129ed5fadd28e526c43397c79775194b5c.tar.xz | |
efi: Allow drivers to reserve boot services forever
Today, it is not possible for drivers to reserve EFI boot services for
access after efi_free_boot_services() has been called on x86. For
ARM/arm64 it can be done simply by calling memblock_reserve().
Having this ability for all three architectures is desirable for a
couple of reasons,
1) It saves drivers copying data out of those regions
2) kexec reboot can now make use of things like ESRT
Instead of using the standard memblock_reserve() which is insufficient
to reserve the region on x86 (see efi_reserve_boot_services()), a new
API is introduced in this patch; efi_mem_reserve().
efi.memmap now always represents which EFI memory regions are
available. On x86 the EFI boot services regions that have not been
reserved via efi_mem_reserve() will be removed from efi.memmap during
efi_free_boot_services().
This has implications for kexec, since it is not possible for a newly
kexec'd kernel to access the same boot services regions that the
initial boot kernel had access to unless they are reserved by every
kexec kernel in the chain.
Tested-by: Dave Young <dyoung@redhat.com> [kexec/kdump]
Tested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> [arm]
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Leif Lindholm <leif.lindholm@linaro.org>
Cc: Peter Jones <pjones@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Diffstat (limited to 'include/linux/efi.h')
| -rw-r--r-- | include/linux/efi.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/efi.h b/include/linux/efi.h index 987c18f6fcae..3fe4f3c47834 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -944,6 +944,7 @@ extern u64 efi_mem_attribute (unsigned long phys_addr, unsigned long size); extern int __init efi_uart_console_only (void); extern u64 efi_mem_desc_end(efi_memory_desc_t *md); extern int efi_mem_desc_lookup(u64 phys_addr, efi_memory_desc_t *out_md); +extern void efi_mem_reserve(phys_addr_t addr, u64 size); extern void efi_initialize_iomem_resources(struct resource *code_resource, struct resource *data_resource, struct resource *bss_resource); extern void efi_reserve_boot_services(void); |